I had this same exact issue, my humidity was at 99% using Forest Floor, it just retained moisture way too much. I changed my substrate to Komodo Coconut Terrain / Exo Terra Jungle Earth mix, and my humidity went down to the 60-77% range, which in my opinion is pretty perfect. That being said, remember that humidity in Western and Central Africa are often consistently at 77 up to even 88%; our bp's won't suffer in high humidity as long as they are not laying on wet bedding consistently, and the enclosure isn't condensed or fogged up. Living in an area where it's humid in the begin with, I'd really recommend a dry substrate, and possibly a smaller water dish, to get the humidity down. My humidity issues were resolved when I changed the substrate to much drier.